Autoimmune disease

Autoimmunity is the failure of an organism to recognize its own constituent parts (down to the sub-molecular levels) as "self", which results in an immune response against its own cells and tissues. Any disease that results from such an aberrant immune response is termed an autoimmune disease. Prominent examples include Coeliac disease, diabetes mellitus type 1 (IDDM), systemic lupus erythematosus (SLE), Sjögren's syndrome,  multiple sclerosis (MS), Hashimoto's thyroiditis, Graves' disease, idiopathic thrombocytopenic purpura, and rheumatoid arthritis (RA). See List of autoimmune diseases.
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Autoimmune disease n. A disease resulting from an immune reaction produced by an individual's white blood cells or antibodies acting on the body's [more]Autoimmune disease - Community and Resources

Noun
1. any of a large group of diseases characterized by abnormal functioning of the immune system that causes your immune system to produce antibodies against your own tissues
(synonym) autoimmune disorder
(hypernym) disease
(hyponym) type I diabetes, insulin-dependent diabetes mellitus, IDDM, juvenile-onset diabetes, juvenile diabetes, growth-onset diabetes, ketosis-prone diabetes, ketoacidosis-prone diabetes, autoimmune diabetes
(part-meronym) autoimmunity

adjective
referring to an immune reaction in a person to antigens in his own tissue
autoimmune disease = disease where the patient's own cells are attacked by autoantibodies; rheumatoid arthritis is thought to be an autoimmune disease

A condition in which the body recognizes its own tissues as foreign and directs an immune response against them.